The present invention relates to door locks, and more particularly, to a so called "panic proof" interconnected locking mechanism having a separate latch bolt and dead bolt designed for installation in round bored openings in the edge and face of a door stile. A single action turn of the inside lever simultaneously retracts both latch and bolt for immediate exit.
A high security lock system for a building door normally involves both a latch bolt, for convenience in opening and closing a door, and a dead bolt for securely locking the door. Customarily, the dead bolt penetrates the jamb over an inch in order to protect against the possibility of the jamb or door being sprung enough to disengage the bolt from the jamb and may be extended and retracted with a key from the outside or a thumb turn from the inside. The latch bolt is normally knob operated from either side.
There have been a disturbing number of instances in which a person on the inside of a building in a panic situation, such as a fire or an earthquake, has failed to open a door leading to safety. This is simply because many people, under such panic conditions, fail to realize that the dead bolt and latch bolt must be both retracted in order to open the door.
To avoid such problem, there have been introduced the use of so-called "panic proof" locks. In "panic proof" locks, the latch bolt and dead bolt are independent mechanisms, as always, but an additional mechanism is provided to couple the interior knob to the dead bolt so that when the interior knob is turned, not only is the latch bolt retracted, but the dead bolt, if extended, is also retracted.
Prior art mechanisms for accomplishing the desired result are generally relatively complicated devices using levers and gears in combination. These devices are also unidirectional, that is, different parts are required for a lock for a left opening door and for a right opening door, resulting in extra expense and inconvenience.
U.S. Pat. No. 4,129,019 issued to Urdal entitled "Cartridge For A Lockset" has disclosed a rather simple lock construction, which can be installed in either left or right opening doors. In which, two individual, standard devices, collectively referred to as a lockset, are utilized on a door panel in connection with the door frame. The lock devices, usually entirely independent of each other, are joined together by a cartridge device interengaging with the spindles of the individual locks. The cartridge contains a mechanism for actuating both of the standard locks from one of the lock operators and is relatively thin and can be unobtrusively applied to installations already in existence and to new installations. The usual environment for the lockset cartridge is in connection with a door panel mounted on hinges in a door frame in a surrounding wall. The frame is provided with one or more strike boxes arranged to receive two bolts, a latch bolt and a dead bolt. In many installations the latch bolt is provided with a keyed operator on the exterior and a knob on the interior. The dead bolt is provided with a key actuator on the exterior and a thumb turn on the interior. The latch bolt mechanism governed by the controllers is a standard, independent lockset readily available and of a kind already installed on many door panels. Comparably, the mechanism of the dead bolt structure controlled by the key and the operator is itself a separate, standard mechanism as already installed in many door panels.
Urdal disclosure is useful when operated by a normal healthy person, but not when it is operated by a handicapped user. Lever type handles, as opposed to knob type handle, are preferably connected to the latch bolt mechanism for the convenience of handicapped users. However, lever type handles are not as rigid as knob type handles. Thus, a panic proof locksets of lever type handles need improvements and some sort of structural reinforcements to satisfy the requirements of handicapped users.
The function that rotation of the controller by itself will retract both the latch bolt and the dead bolt is valuable in a panic situation and though has been accomplished in Urdal's lock, it is done in an incomplete fashion. The cartridge has a drive ring which restricts the movement of the screws along the arcuate aperture and that the latch bolt need to be cut down in a shorter length. Herein the aim is to utilize a collar and to provide an extra rotation of about 20 degrees of the screw along the arcuate aperture such that the latch bolt need not be cut down into a shorter length.